The Puzzle of the Tile-Fish.
that there had been a progressive movement of the warm body
of water toward the shore, and saw plainly that if the same rate
were to hold good this year the whole of the continental edge of
the area in question would in all probability be covered by the
warm water. The idea then suggested itself that if such were the
case the conditions for the reappearance of the tile-fish would
be established, if environment meant anything in the case. The
fish had been previously in a depth of water varying from 70
to 120 fathoms, and its feeding ground, being on the bottom,
would occur just at the edge of the platform. It was probably,
moreover, a tropical deep-sea fish, and the temperature at which
it was caught (50° to 580) could only be established on the
New England coast by just such an invasion of the continental
edge as has been described. It is only necessary to conceive
that the whole of the continental edge from Florida to Nantucket
is thus overflowed by this warm band of water to see how the
regular feeding ground of a tropical fish could be extended so
that the fish could follow it throughout the whole of this largely
increased area.
While in the midst of this interesting theoretic work I was
aroused by a letter from Washington, from Colonel McDonald,
stating that owing to an economical turn, Congress had largely
reduced the appropriation for the Commission, so that we should
have to give up a great portion of the scientific work. I went
to Washington with my facts, and they interested the Commis
sioner to such an extent that he agreed to give me the chance
to test the theory, and further expressed a wish to take part in
the work himself.
We first went out south of Marthas Vineyard, found that
the temperature was right, set the trawl lines and 'caught the
fish. During the next two months I spent considerable time in
tracing up the area over which the temperature of 50° and over
was to be found on the continental edge, fishing at the same
time with the trawls to see if the fish were there. We found
them all the way to the Delaware capes, and were satisfied that
though they were not numerous they had taken advantage of
changed conditions over the area to occupy an enlarged feeding
ground.
The explanation of the disappearance of the fish in 1882, as
suggested by Colonel McDonald, seems now to cover the ground
165